Boron carbide (B4C) is a covalently-bonded solid with a high melting point (2427° C.), an extremely high hardness (Vickers hardness: 2400 kg/mm2), a low density (2.52 g/cm3) and a high neutron absorption cross-section. It is a solid solution with carbon in the range 8.8-20.0 mol %. Boron carbide has been used for light-weight ceramic armor, for wear-resistant components such as blasting nozzles and grinding wheels, and for control rods in nuclear reactors
Sintering of pure boron carbide to high densities has proven difficult. Specific additives (sintering aids such as carbon, Al2O3 and TiB2) or hot pressing have been used to achieve near full density. B4C powders are typically hot-pressed at about 2100° C. and under 30-40 MPa uniaxial pressure to obtain dense articles.